Table 2.
Comparison of density (number per unit area of leaf) and relative abundance of epidermal cells in cotyledons and the first leaves of garden cress and response of epidermal cell density to variations in the internal CO2 concentration of the leaf (Ci)
| Age (DAW) | Cotyledons |
First leaves |
||||
|---|---|---|---|---|---|---|
| SD (mm–2) | PCD (mm–2) | SI (%) | SD (mm–2) | PCD (mm–2) | SI (%) | |
| 7 | 439 (25) | 1308 (70) | 25·2 (1·4) | |||
| 14 | 186 (11) | 535 (30) | 25·8 (2·4) | 535 (84) | 1304 (223) | 29·4 (2·0) |
| Slope of Ci response (mol μmol–1 mm–2 or % mol μmol–1 where marked *), (R2) | 0·017 (0·009) | –0·056 (0·011) | 0·0019* 0·0407) | –0·793 (0·549) | –2·511 (0·703) | 0·0069* (0·317) |
Density of stomata (SD) and pavement cells (PCD) per mm2 of projected leaf area (sum of adaxial and abaxial values) and stomatal index (SI) in cotyledons 7 and 14 d after seed watering (DAW) and in the first leaves 14 DAW are given.
Means and standard error of the means (in parentheses) are shown of sets obtained by pooling data from plants grown in three growth CO2 concentrations (180, 400 and 800 μmol mol–1), two air humidities (60 and 90 %), two different inert host gases (N2 and He) or reduced atmospheric pressure (n = 18, each n is a mean of three measurements on individual plants). Standard errors of SI means were calculated as means over all 18 treatments each obtained by the formula shown in the Materials and Methods.